U.S. patent number 5,875,047 [Application Number 08/583,633] was granted by the patent office on 1999-02-23 for optical transceiver unit.
This patent grant is currently assigned to Fujitsu Limited. Invention is credited to Akio Abe, Shigeichi Izumi, Mitsuru Yumoto.
United States Patent |
5,875,047 |
Abe , et al. |
February 23, 1999 |
**Please see images for:
( Certificate of Correction ) ** |
Optical transceiver unit
Abstract
An optical receiver unit has an optical receiver module which
includes an opto-electric converter housed in a metal container, a
printed-circuit board having power, signal and ground terminals
connected to the opto-electric converter, a casing body which
includes a board receptacle and a module receptacle, respectively
for accommodating the printed-circuit board and the optical
receiver module, and a cover for covering the casing body. The
casing body and the cover are both molded out of synthetic resin
and have respective, first and second metallized internal surfaces.
The cover covers the casing body so that the second metallized
internal surface of the cover contacts the first metallized
internal surface of the casing body. The ground line is connected
to the metal container of the optical receiver module.
Inventors: |
Abe; Akio (Kawasaki,
JP), Izumi; Shigeichi (Kawasaki, JP),
Yumoto; Mitsuru (Kawasaki, JP) |
Assignee: |
Fujitsu Limited (Kawasaki,
JP)
|
Family
ID: |
26334379 |
Appl.
No.: |
08/583,633 |
Filed: |
January 5, 1996 |
Foreign Application Priority Data
|
|
|
|
|
Jan 9, 1995 [JP] |
|
|
7-001195 |
Sep 20, 1995 [JP] |
|
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7-242073 |
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Current U.S.
Class: |
398/135 |
Current CPC
Class: |
H04B
10/60 (20130101) |
Current International
Class: |
H04B
10/06 (20060101); H04B 010/00 (); H04B 010/04 ();
H04B 010/06 () |
Field of
Search: |
;359/163,180,152,189
;455/90,128,347 ;361/720,730,748,752 ;385/35 ;257/81,99 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Nozu, Chapter II, "Theory Required for Noise Processing" (the
latest technology of a countermeasure against noise), Jul. 1986,
pp. 7-61 with an English language translation consisting of pp.
1-109 and a 9-page translation of the drawings. .
Patent Abstracts of Japan, vol. 127 (E-1516) & JP-A-5-315767
filed Nov. 26, 1993, Tsuzumi, "Excess Length Processing Structure
for Optical Fiber"..
|
Primary Examiner: Negash; Kinfe-Michael
Attorney, Agent or Firm: Staas & Halsey
Claims
What is claimed is:
1. An optical receiver unit, comprising:
an optical receiver module having an opto-electric converter which
converts an optical signal into an electrical signal;
a printed-circuit board having a terminal connected to the
opto-electric converter;
a casing body molded out of synthetic resin and defining a
receptacle therein accessible through an opening in the casing body
and having a first metallized internal surface surrounding the
receptacle, the receptacle comprising:
a board receptacle portion which accommodates said printed-circuit
board, and
a module receptacle portion which accommodates said optical
receiver module; and
a cover, molded out of synthetic resin and having a second
metallized internal surface, received on and covering the opening
in said casing body so that the second metallized surface of said
cover contacts the first metallized surface of said casing
body.
2. An optical receiver unit according to claim 1, further
comprising:
a metal container which houses the opto-electric converter; and
signal and ground terminals on the printed circuit board connected
to the opto-electric converter via signal and ground lines,
respectively; and
a ground circuit wiring the ground line to the metal container of
said optical receiver module.
3. An optical receiver unit according to claim 2, wherein said
ground circuit comprises first and second ground lines wired on
respective, first and second opposite sides of the signal line and
in parallel with a surface of said printed-circuit board.
4. An optical receiver unit according to claim 1, wherein the
synthetic resin, out of which said casing body and said cover are
molded, further comprises a conductive material mixed therein.
5. An optical receiver unit according to claim 1, wherein:
said board receptacle portion comprises an elastic first claw for
clutching said printed-circuit board to said board receptacle
portion;
said module receptacle portion comprises an elastic fitting which
clutches said optical receiver module to said module receptacle
portion; and
one of said casing body and said cover further comprises an elastic
claw and the other of said casing body and said cover further
comprises a claw engaging surface, the claw selectively engaging
the claw engaging surface and clutching said cover and said casing
body together.
6. An optical receiver unit according to claim 5, wherein said
first claw is constructed of a material and in a configuration so
as to elastically deform and thereby to allow said printed-circuit
board to be forcibly inserted into said board receptacle portion
and, when said printed-circuit board has been so inserted, so as to
elastically restore and thereby to clutch said printed-circuit
board to said board receptacle portion.
7. An optical receiver unit according to claim 5, wherein:
said module receptacle portion further comprises a hole; and
said fitting and said hole are constructed of respective materials
and configurations such that said fitting elastically deforms when
being forcibly inserted into said hole and, when fully inserted
into said hole, said fitting elastically restores thereby to clutch
said optical receiver module to said module receptacle portion.
8. An optical receiver unit according to claim 5,
wherein said second claw is provided on said casing body and is
constructed of a material and a configuration such that when said
cover is forced to a closed position with respect to said casing
body, said second claw elastically deforms to allow said cover to
be closed and, when said cover is closed, said second claw
elastically restores thereby to clutch said cover to said casing
body.
9. An optical transmitter unit, comprising:
an optical transmitter module having an electro-optical converter
which converts an electric signal into an optical signal;
a printed-circuit board having a terminal connected to the
electro-optical converter;
a casing body molded out of synthetic resin and defining a
receptacle therein accessible through an opening in the casing body
and having a conductive property on at least an internal surface of
the receptacle, the receptacle, comprising:
a board receptacle portion which accommodates said printed-circuit
board, and
a module receptacle portion which accommodates said optical
transmitter module; and
a cover, molded out of a synthetic resin and having a conductive
property on at least an interior surface thereof, received on and
covering the opening in said casing body so that the second
metallized surface of the said cover contacts the first metallized
surface of the said casing body.
10. An optical transmitter unit according to claim 9, wherein:
said board receptacle portion further comprises an elastic claw for
clutching said printed-circuit board to said board receptacle
portion;
said module receptacle portion further comprises an elastic fitting
which clutches said optical transmitter module to said module
receptacle portion, and
one of said casing body and said cover further comprises an elastic
claw and the other of said casing body and said cover further
comprises a claw engaging surface, the claw selectively engaging
the claw engaging surface and clutching said cover and said casing
body together.
11. An optical transmitter unit as recited in claim 9, wherein the
synthetic resin, out of which said casing body and said cover are
molded, further comprises a conductive material mixed therein.
12. An optical transmitter unit as recited in claim 9, wherein the
casing body and the cover have respective internal metallized
surfaces, the metallized surface of the cover contacting that of
the casing body when the cover is received on the casing body,
covering the opening therein.
13. An optical transceiver unit, comprising:
an optical receiver module having an opto-electric converter which
converts an optical signal into an electrical signal;
an optical transmitter module having an electro-optical converter
which converts an electric signal into an optical signal;
a printed-circuit board having terminals connected to the
opto-electric converter and the electro-optical converter;
a casing body, molded out of synthetic resin, defining a receptacle
therein accessible through an opening in the casing body and having
a first metallized internal surface surrounding the receptacle, the
receptacle comprising,
a board receptacle portion which accommodates said printed-circuit
board,
a receiver module receptacle portion which accommodates said
optical receiver module, and
a transmitter module receptacle portion which accommodates said
optical transmitter module; and
a cover, molded out of synthetic resin and having a second
metallized internal surface, received on and covering the opening
in said casing body so that the second metallized surface thereof
contacts the first metallized surface of said casing body.
14. An optical transceiver unit according to claim 8, further
comprising:
a metal container which houses the opto-electric converter; and
signal and ground terminals on the printed circuit board connected
to the opto-electric converter via signal and ground lines,
respectively; and
a ground circuit wiring the ground line to the metal container of
said optical receiver module.
15. An optical transceiver unit according to claim 14, wherein said
ground circuit comprises first and second ground lines wired on
respective, first and second opposite sides of the signal line and
in parallel with a surface of said printed-circuit board.
16. An optical transceiver unit according to claim 13, wherein the
synthetic resin, out of which said casing body and said cover are
molded, further comprises a conductive material which is mixed
therein.
17. An optical transceiver unit according to claim 13, wherein:
said board receptacle portion further comprises an elastic claw
which clutches said printed-circuit board to said board receptacle
portion;
said receiver module receptacle portion further comprises an
elastic fitting which clutches said optical receiver module to said
receiver module receptacle portion;
said transmitter module receptacle portion further comprises an
elastic fitting which clutches said optical transmitter module to
said transmitter module receptacle portion; and
one of said casing body and said cover further comprises an elastic
claw and the other of said casing body and said cover further
comprises a claw engaging surface, the claw selectively engaging
the claw engaging surface and clutching said cover and said casing
body together.
18. An apparatus, comprising:
an opto-electric converter;
a printed-circuit board having a terminal connected to the
opto-electric converter;
a casing body, of a molded synthetic resin material, defining a
receptacle therein accessible through an opening in the casing body
and having a first metallized internal surface surrounding the
receptacle, the receptacle including:
a first receptacle portion which accommodates said printed-circuit
board, and
a second receptacle portion which accommodates said opto-electric
converter; and
a cover, of a molded synthetic resin material and having a second
metallized internal surface, received on and covering the opening
in said casing body so that the second metallized internal surface
of said cover contacts the first metallized internal surface of
said casing body.
19. The apparatus according to claim 18, further comprising:
a metal container which houses the opto-electric converter; and
signal and power terminals on the printed circuit board connected
to the opto-electric converter via signal and power lines,
respectively; and
a ground circuit wiring a ground level of said printed circuit
board to said metal container.
20. The apparatus according to claim 19, wherein:
said ground circuit comprises first and second lines wired on
respective, first and second opposite sides of at least the signal
line and in parallel with a surface of said printed-circuit
board.
21. The apparatus according to claim 18, wherein the synthetic
resin material further comprises a material having high thermal
conductivity, relatively to the thermal conductivity of the
synthetic resin, mixed with the synthetic resin.
22. The apparatus according to claim 18, wherein:
said first receptacle portion further comprises an elastic first
claw for clutching said printed-circuit board to said first
receptacle portion;
said second receptacle portion further comprises an elastic fitting
which clutches said opto-electric converter to said second
receptacle portion; and
one of said casing body and said cover further comprises an elastic
second claw and the other of said casing body and said cover
further comprises a claw engaging surface, the second claw
selectively engaging the claw engaging surface and clutching said
cover and said casing body together.
23. The apparatus according to claim 22, wherein said first claw is
constructed of a material and in a configuration so as to
elastically deform and thereby to allow said printed-circuit board
to be forcibly inserted into said first receptacle portion and,
when said printed-circuit board has been so inserted, so as to
elastically restore and thereby to clutch said printed-circuit
board to said first receptacle portion.
24. The apparatus according to claim 22, wherein:
said second receptacle portion further comprises a hole; and
said fitting and said hole are constructed of respective materials
and configurations such that said fitting elastically deforms when
being forcibly inserted into said hole and, when fully inserted
into said hole, said fitting elastically restores thereby to clutch
said opto-electric converter to said second receptacle portion.
25. The apparatus according to claim 22, wherein said second claw
is provided on said casing body and constructed such that when said
cover is forced to close, said second claw elastically deforms to
allow said cover to be closed and, when said cover has been closed,
said second claw elastically restores to clutch said cover to said
casing body.
26. An apparatus, comprising:
an electro-optical converter;
a printed-circuit board having a terminal connected to the
electro-optical converter;
a casing body of a molded synthetic resin material defining a
receptacle therein accessible through an opening in the casing body
and having an electrical conductive property on at least an
internal surface of the receptacle, the receptacle including:
a first receptacle portion which accommodates said printed-circuit
board, and
a second receptacle portion which accommodates said electro-optical
converter; and
a cover, of a molded synthetic resin material and having an
electrical conductive property on at least an internal surface
thereof, received on and covering the opening in said casing body
so that the internal surface, having an electrical conductive
property, of said cover contacts the internal surface, having an
electrical conductive property, of said casing body.
27. The apparatus according to claim 26, wherein:
said first receptacle portion further comprises an elastic claw for
clutching said printed-circuit board to said board receptacle
portion;
said second receptacle portion further comprises an elastic fitting
which clutches said electro-optical converter to said module
receptacle portion; and
one of said casing body and said cover further comprises an elastic
claw and the other of said casing body and said cover further
comprises a claw engaging surface, the claw selectively engaging
the claw engaging surface and clutching said cover and said casing
body together.
28. The apparatus as recited in claim 26, wherein the synthetic
resin material further comprises a conductive material mixed
therein.
29. The apparatus as recited in claim 26, wherein the casing body
and the cover have respective internal metallized surfaces, the
metallized surface of the cover contacting that of the casing body
when the cover is received on the casing body, covering the opening
therein.
30. An apparatus, comprising:
an opto-electric converter;
an electro-optical converter;
a printed-circuit board having terminals connected to the
opto-electric converter and the electro-optical converter;
a casing body, of a molded synthetic resin material, defining a
receptacle therein accessible through an opening in the casing body
and having a first metallized internal surface surrounding the
receptacle, the receptacle including:
a first receptacle portion which accommodates said printed-circuit
board,
a second receptacle portion which accommodates said opto-electric
converter, and
a third receptacle portion which accommodates said electro-optic
converter; and
a cover, of a molded synthetic resin material and having a second
metallized internal surface, received on and covering the opening
in said casing body so that the second metallized surface thereof
contacts the first metallized surface of said casing body.
31. The apparatus according to claim 30, further comprising:
a metal container which houses the opto-electric converter;
signal and power terminals on the printed circuit board connected
to the opto-electric converter via signal and power lines,
respectively; and
a ground circuit wiring a ground level of said printed circuit
board to said metal container.
32. The apparatus according to claim 31, wherein:
said ground circuit comprises first and second lines wired on
respective, first and second opposite sides of at least the signal
line and in parallel with a surface of said printed-circuit
board.
33. The apparatus according to claim 30, wherein the synthetic
resin material further comprises a material having high thermal
conductivity, relatively to the thermal conductivity of the
synthetic resin, mixed with the synthetic resin.
34. The apparatus according to claim 30, wherein:
said first receptacle portion further comprises an elastic claw
which clutches said printed-circuit board to said board receptacle
portion;
said second receptacle portion further comprises an elastic fitting
which clutches said opto-electric converter to said second
receptacle portion;
said second receptacle portion further comprises an elastic fitting
which clutches said opto-electric converter to said third
receptacle portion; and
one of said casing body and said cover further comprises an elastic
claw and the other of said casing body and said cover further
comprises a claw engaging surface, the claw selectively engaging
the claw engaging surface and clutching said cover and said casing
body together.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical transceiver unit used
for transmitting and/or receiving an optical signal. In the field
of electronics and communication, in order to transfer or
interchange a great volume of information at a high speed within or
between electronic equipment, an optical signal is transmitted
through an optical fiber as a transmission line. An electric signal
carrying information is converted into an optical signal for
transmission and the optical signal is converted into an electric
signal for processing the information.
Therefore, an opto-electric converter (optical receiver unit) and
an electro-optical converter (optical transmitter unit) which are
small-sized, high-speed, highly reliable and also easy in
manufacturing and operation, are in great demand.
2. Description of the Related Art
An optical transceiver unit including the optical receiver unit and
optical transmitter unit in a one-piece construction, is
acknowledged as prior art.
FIGS. 1A-1C are top, front and side plan views, respectively of a
casing body.
The casing body 1 is made by bending a sheet of metal along four
sides there of to form a case with a bottom 2 surrounded by a wall
and by welding an L-shaped metal strip 3 to the bottom 2 to form a
partition wall 3a for dividing the case into left and right
chambers. Rectangular holes, or slots, 4, 5 are bored in the
respective chambers.
Four curved projections 8 are extended and extend inwardly, two
each from right and left sidewalls 6, 7 close to the bottom 2, to
position and support a printed circuit board. The upper surface of
the projection 8 is equal to that of the partition 3 in height
above the bottom 2. A projection strip 9 is formed by punching, at
a distance equal to the thickness of the printed circuit board
above each of the projections 8, thereby to have the printed
circuit board inserted therebetween. Four projections 11 extrude
(extend) outwardly, two each from the sidewalls 6, 7 close to the
bottom 2. Projections 12 are formed in the respective centers of
the side walls 6, 7 by punching and bending such that the bottom of
each declines outwardly for latching a casing cover.
Corresponding to the right and left chambers formed by the
partition 3, holes 14 are provided in the front wall 13,
respectively for mounting an optical receiver module and an optical
transmitter module therein. A bend 16 is provided on the partition
wall 3a to position the front end of the printed circuit board. The
casing body 1, which is made of structural sheet steel, is
nickel-plated to improve conductivity and to prevent rusting.
FIG. 2 shows the casing body 1 having a printed circuit board 17,
an optical receiver module 18 and an optical transmitter module 19
mounted therein.
The four-layer printed circuit board 17 is mounted such that it
fits in an area enclosed by the side walls 6, 7, the rear wall of
the casing body 1 and the bend 16 of the partition 3. It is
supported in position on the respective upper surfaces of the
projections 8 and the partition wall 3a. Then, the projections 9 of
the right and left sidewalls 6, 7 are bent over the printed circuit
board 17 and soldered to respective ground patterns 21 printed
thereon.
For easy understanding, electronic parts mounted on the printed
circuit board 17 are not shown in FIG. 2. The printed circuit board
17 has lead terminals 22 arranged in a line and projecting
downwardly through the rectangular holes 4, 5, to connect to a main
printed circuit board. On one side of the casing-body front wall
13, the optical receiver module 18 is fastened to a flange 24 of a
metal case 23 with screws 25. The metal case 23 houses a photo
diode for performing opto-electric conversion, built in a metallic
container.
Wires for supplying a bias voltage to the photo diode, outputting
an electric signal and outputting ground signals for the output
signal and the metallic container are soldered to a connection
pattern 26 printed on a side of the printed circuit board 17. An
end of an optical fiber 27 is connected to the optical receiver
module 18 and the other end to an optical connector 28.
On the other side of the casing-body front wall 13, the optical
transmitter module 19 is fastened to a flange 32 of a metal case 31
with screws 33. The metal case 31 houses a laser diode for
performing electro-optical conversion, built in a metallic
container. A wire for supplying power to the laser diode and a wire
for connecting to a monitor laser diode are soldered to connection
patterns 34 printed on the side of the printed circuit board 17. An
end of an optical fiber 35 is connected to the optical transmitter
module 19 and the other end to an optical connector 36.
FIGS. 3A-3C are inside, front and side plan views, respectively of
a casing body.
The casing cover 41 is made by bending a sheet metal along the four
sides there of to form a case surrounded by a wall. An L-shaped
metal strip is welded to an upper surface 42 to form a partition
wall 43a dividing the case into two components. Rectangular holes
46 are bored in the respective centers of the right and left
sidewalls 44, 45. Two holes 47 are bored at the respective front
and rear edges of the sidewalls 44, 45 close to the aperture (i.e.,
top opening) of the case. A gap 49 is provided on the right and
left sides of the front wall segments, 48. The casing cover 41,
which is made of the structural sheet steel board, is nickel-plated
for finishing to improve conductivity and to prevent rusting.
FIG. 4A is front plan view of an assembly of the conventional
optical transceiver unit (optical connecters 28, 36 not shown).
FIG. 4B is a front sectional view of an assembly of the
conventional optical transceiver unit.
In FIG. 4A, the casing cover 41 fits on the the casing body 1 to
cover its opening. The optical receiver module 18 and optical
transmitter module 19 within the gaps 49 provided on the front side
of the casing cover 41.
In FIG. 4B, the projection strips 12 provided on both of the
casing-body sidewalls 6, 7 fit in the rectangular holes 46 provided
on the casing-cover sidewalls 44. A flat surface of the rectangular
hole 46 engages with a side of the projection 12 to prevent the
casing cover 41 from coming off the casing body 1. The projections
11 provided on the casing-body sidewalls 6, 7 fit in the front and
rear holes 47 of the casing-cover sidewalls 44, 45 to prevent
backlash and reenforce electric contact between the the casing body
1 and casing cover 41. Since the casing-body partition wall 3a and
casing-lid partition 42 electrically isolate the right and left
chambers, each accommodating the optical transmitter circuit and
optical receiver circuit mounted on the printed circuit board 17,
electromagnetic interference between the circuits is reduced.
In each chamber, a resin-covered IC bear chip is mounted under the
printed circuit board 17. On a side of each compartments, lead
terminals 22 project downwardly for connecting the optical
transceiver unit to a main printed-circuit board. In the
conventional optical transceiver unit as described above, the
casing body 1 and the casing cover 41 are both made of sheet metal
and to mount the optical receiver module 18 and optical transmitter
module 19, the flanges 24, 32 are provided and fastened to the
casing body with screws 25, 33.
Therefore, it is a problem that a large area is required for
mounting the modules, accordingly rendering the unit large-sized
and heavy. It is another problem that a burdensome manufacturing
process is required for mounting the printed circuit board 17 on
the casing body 1, for example, for providing the partition 3, the
projections 8 and the bend 16 for positioning the printed circuit
board 17, and for bending the projection 9 and soldering the wires
to the printed-circuit-board ground patterns 21.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an optical
receiver unit which is small-sized, light-weight and easy in
assembling. It is another object of the present invention to
provide such a unit which is reliable and fail proof against
electromagnetic interference.
To achieve the above and other objects, the optical receiver unit
of the present invention provides an optical receiver module having
an opto-electric converter contained in a metal container, a
printed-circuit board having power, signal and ground terminals for
connecting power, signal and ground lines to the opto-electric
converter, a casing body including a board receptacle and a module
receptacle respectively for accommodating the printed-circuit board
and the optical receiver module, and a cover for covering the
casing body.
The casing body and the cover are both molded out of synthetic
resin and have at least an internal surface metallized. The cover
covers the casing body so that the metallized surface of the cover
contacts that of said casing body.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A-1C are top, front and side plan views, respectively of a
casing body;
FIG. 2 shows the casing body 1 having a printed circuit board 17,
an optical receiver module 18 and an optical transmitter module 19
mounted thereon;
FIGS. 3A-3C are inside, front and side plan views, respectively of
a casing body;
FIG. 4A is front plan view of an assembly of the conventional
optical transceiver unit (optical connecters 28, 36 being not shown
therein);
FIG. 4B is a front sectional view of the assembled conventional
optical transceiver unit;
FIG. 5 is a top view showing the external appearance of an optical
transceiver unit of the first embodiment of the present
invention.
FIGS. 6A-6C are top, side and front views, respectively, of a
casing body;
FIG. 7 shows the casing body 61 with a printed circuit board 81,
optical receiver module 53 and optical transmitter module 54
mounted thereon;
FIGS. 8A-8C are traverse sectional views illustrating a process of
mounting the printed circuit board 81 in the casing body 61;
FIGS. 9A-9E are traverse sectional views illustrating a process of
mounting the optical receiver module 53 in the module receptacle
71;
FIG. 10A is a longitudinal sectional view of the optical receiver
module 53;
FIGS. 10B and 10C are traverse sectional views of the optical
receiver module 53 taken from the wire side and optical fiber side,
respectively;
FIG. 11A is a longitudinal sectional view of the optical
transmitter module 54;
FIGS. 11B and 11C are traverse sectional views of the optical
transmitter module 54 taken from the wire side and optical fiber
side, respectively;
FIG. 12A is a plan view of a connection between the optical
receiver module 53 and printed circuit board 81;
FIG. 12B is a side view of the connection between the optical
receiver module 53 and printed circuit board 81 taken from the wire
side;
FIG. 13A is a plan view of a connection between the optical
transmitter module 54 and the printed circuit board 81;
FIG. 13B is a side view of the connection between the optical
transmitter module 54 and the printed circuit board 81, taken from
the wire side;
FIGS. 14A-14C are inside, front and side plan views, respectively
of a casing lid;
FIG. 15A is a longitudinal sectional view of the assembled optical
transceiver unit, with both the rear- and front-side claws 156, 157
latched with the casing-body grooves 69 and 73, respectively;
FIG. 15B is a traverse sectional view of the assembled optical
transceiver unit, with both the rear- and front-side claws 156, 157
latched with the casing-body grooves 69 and 73, respectively;
FIGS. 16A-16C are top, side and front views, respectively, of a
casing body;
FIG. 16D is a sectional view taken along the line 16D--16D of FIG.
16A;
FIGS. 17A-17C are inside, front and side views, respectively of a
casing cover;
FIG. 18A is a side view in cross section of the assembled optical
transceiver unit, with both the rear- and front-side claws 156 and
157 latched with the casing-body grooves 69 and 73,
respectively;
FIG. 18B is a front view in cross section of the assembled optical
transceiver unit;
FIGS. 19A and 19B are top and side external views, respectively of
the optical receiver unit of a third embodiment of the present
invention;
FIG. 20A is a top view of the casing body of a main body 182;
FIG. 20B shows the casing body 183 with the printed circuit board
811 and optical receiver module 53 mounted thereon; and
FIGS. 21A-21C are inside, front and side views, respectively of a
casing cover.
Throughout the above-mentioned drawings, identical reference
numerals are used to designate the same or similar component
parts.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
An optical transceiver unit embodying the present invention is
explained in detail referring to the figures.
FIG. 5 is a top view showing a external appearance of an optical
transceiver unit of the first embodiment of the present
invention.
An optical receiver module 53 and an optical transmitter module 54
are housed in a main body 52 of the optical unit 51. Optical fibers
55, 56 are connected respectively at first ends thereof to the
modules and at second ends thereof to optical connectors 57, 58.
FIGS. 6A-6C are top, side and front views, respectively of a casing
body. It is assumed in FIG. 6A that the right, left, upper, lower,
reverse and obverse sides of the page are the front, rear, right,
left, bottom and top sides of the unit, respectively.
The casing body 61 is molded as a one-piece construction, out of a
synthetic resin having excellent moldability and strength, such as
an ABS resin. The casing body 61 is shaped like a container having
a base 64 surrounded by a wall 62. To mount a printed circuit
board, steps 63 of a predetermined height above the base 64 are
provided at four corners of the wall 62. Claws for latching the
printed circuit board in position extend from the right and left
walls 62.
Rectangular holes 66, 67, for letting (i.e., passing)
printed-circuit-board lead terminals therethrough, are provided on
the right and left sides of the base 64. The wall 62 has a step 68
cnstructed such that the inner level of the top is higher than the
outer. Grooves 69 for receiving casing-cover claws are provided
right and left on the outside of the rear wall 62.
Module receptacles 71, 72 for holding an optical receiver module
and an optical transmitter module, respectively extend in parallel
from the front wall 62. Grooves 73 for receiving casing-lid claws
are provided on the wall 62 of both sides of the module receptacles
71, 72.
The grooves 69, 73 each have a recess 74 formed at their bottoms on
the casing-body base 64. The module receptacles 71, 72 are provided
with semicircular recesses 75, 76 where the respective module
external forms fit collar-holding recesses 77, 78 and
clamp-insertion holes 79.
The so-constructed casing body 61 is metallized on the whole
surface through a process, for example, of electroless plating,
copper plating and nickel-plating for glossy finishing.
FIG. 7 shows the casing body 61 with the printed circuit board 81,
optical receiver module 53 and optical transmitter module 54
mounted thereon.
The multi-layer (4- or 8-layer) printed circuit board 81 fits in an
area (board receptacle) formed by the casing-body wall 62, with the
reverse side placed on steps 63 at the four casing-body corners and
with the right and left sides inserted under the claws 65. Since
the printed circuit board 81 contacts the upper surface of the
steps 63 at the four corners, the ground patterns printed on the
four reverse-side corners thereof contact the metallized surface of
the casing body 61 via the upper surfaces of the steps 63, thus
grounding the metallized casing-body surface.
For easy understanding, electronic parts mounted on the printed
circuit board 81 are not shown in FIG. 7. The printed circuit board
81 has lead terminals 85 for connecting to a main printed-circuit
board on which the optical transceiver unit is mounted, extending
downward through the casing-body rectangular holes 66, 67, with a
group of lead terminal 85 arranged in line on the right side at a
predetermined pitch and the others arranged zigzag on the left side
at a narrower pitch.
The optical receiver module 53 is placed in the casing-body module
receptacle 71 and clamped therein with a metal clamp 86. The
optical transmitter module 54 is placed in the module receptacle 72
and clamped therein with a metal clamp 86. The optical receiver
module 53 houses a sealed metal container incorporating a photo
diode circuit for performing opto-electric conversion and a
preamplifier IC for amplifying the converted electric signal, and
is connected to an optical fiber 55.
Four wires from an end of the sealed metal container are soldered
to respective connection patterns 88 printed on a side of the
printed circuit board 81. One of the wires outputs circuit ground
of the aforesaid internal circuits via the metal container. The
other one outputs an electric signal through a glass terminal (not
shown) provided for isolation on the end of the metal container.
The other two, which are connected to a common connection terminal,
respectively supply power to the preamplifier IC and supply a bias
voltage to the photo diode through the glass terminals. Two
additional ground wires 91, 92 are provided on both sides of the
metal container in parallel with the surface of the printed circuit
board 81 and soldered to ground patterns 93, 94, to reinforce the
capability of optical receiver module 53 to stand electromagnetic
interference.
The optical transmitter module 54 houses a sealed metal container
having a laser diode circuit for performing electro-optical
conversion built therein and is connected to an optical fiber 56.
Four wires from the sealed metal container are soldered to
respective connection patterns 95 printed on a side of the printed
circuit board 81. One of the wires outputs circuit ground from the
internal circuit via the metal container. The other one supplies
power to the laser diode and the other two connect to a monitor
laser diode, all through the glass terminals (not shown).
A received signal processing LSI chip 96 and a transmitting signal
processor LSI chip 97 are resin-sealed on the under surface of the
printed circuit board 81 in the respective areas enclosed in dotted
lines in FIG. 7.
FIGS. 8A-8C are traverse sectional views illustrating a process of
mounting the printed circuit board 81 in the casing body 61.
The claws 65 provided on top of the right and left sidewalls 62
overhang the inside of the sidewalls 62 and have sloped surfaces
99, descending inwardly formed on top.
As shown in FIG. 8B, a group of lead terminals 85 provided on a
side of the printed circuit board 81 are inserted into the
rectangular hole 67 in the bottom (wall) 64. The side of the
printed circuit board 81 is inserted between the steps 63 and the
claws 65. The other side of the printed circuit board 81 is applied
on the slopes 99 of the claws 65 with the other group of lead
terminals 85 inserted in the rectangular hole 66. Then, the printed
circuit board 81 is pressed down at the edge portion thereof
touching the slope 99. The above pressing down elastically-deforms
the claws 65 and sidewalls 62, causing them to bend outwardly and
allowing the printed circuit board 81 to pass through the claws 65.
As a result, the printed circuit board 81 is inserted under the
claws 65 and settled on the steps 63, thus being accommodated in
the board receptacle as shown in FIG. 8C.
The above mounting process may be modified by pressing down the
printed circuit board 81 at both ends while keeping it in parallel
with the casing-body bottom 64, accordingly elastically-deforming
both claws 65 and accommodating it in the board receptacle with a
single stroke.
The process of mounting the optical receiver module 53 in the
module receptacle 71 is explained referring to FIGS. 9A-9D the
process for the optical transmitter module 54 is basically the same
as that for the optical receiver module 53. FIGS. 9A-9D are
traverse sectional views illustrating a process of mounting the
optical receiver module 53 in the module receptacle 71. When the
optical receiver module 53 is mounted in the module receptacle 71,
as shown in FIG. 9A, a metallic module main body 101 settles in a
module-receiving recess 102 and the collar 103 settles in the
collar-receiving recess 77.
The collar 103, whose diameter is larger than that of the module
main body 101, has upper and lower flats 104 formed in parallel
with each other. The flats 103 reduce the size of the optical
transmitter unit. The lower flat 103 settles the module main body
101 stably in a module-receiving recess 102 and prevents it from
rotating because it contacts with the bottom of the
collar-receiving recess 77.
The metal clamp 86 is made by bending a nickel-plated sheet metal
(e.g., stainless sheet steel, white metal plate or phosphorus
bronze sheet) in a reversed U shape and providing claws 105
extending upward and inward at each end of the legs. The legs of
the clamp metal 86 are inserted vertically into the holes 79 as
shown in FIG. 9D. The width of the hole 79 is made larger than the
thickness of the metal clamp 86 but smaller than the total
thickness including the claw. The hole 79 has a wide area (cavity
106) formed toward the bottom of the module receptacle 71.
Therefore, pressing down the clamp metal 86 elastically-deforms the
claws 105 to force them into the holes 79 and to contact the
clamp-metal legs with the module main body 101. Further depressing
elastically-deforms both the clamp-metal legs to insert them deep
into the holes 79.
The claw 105 passes through the hole 79 while being contracted and
engages the cavity 106 when it expands by an elastic restoring
force. Thus, the module main body 101 is pressed and fastened to
the module-receiving recess 102 by the elastic restoring force of
the clamp-metal legs. The module main body 101 being fastened to
the module-receiving recess 102 establishes an electrical
connection between the former and the latter's metallized surface.
The claws being pressed to the clamp-metal inner surface
establishes an electrical connection between the former and the
latter's metallized surface, accordingly establishing an electrical
connection between the metal clamp and the module main body
101.
FIG. 10A is a longitudinal sectional view of the optical receiver
module 53. FIGS. 10B and 10C are traverse sectional (and
elevational) views of same taken from the wire side and optical
fiber side, respectively. The optical receiver module 53 houses a
metal container 112 having a photo diode circuit 111 and a
preamplifier integrated circuit (not shown) mounted on its base
113. The circuits are sealed up by a cap 115 which has a lens 114
built in.
One of four wires from the sealed metal container 112 outputs
circuit ground via the metal container 112. The other three
respectively supply a bias voltage to the preamplifier IC, supply a
bias voltage to the photo diode 111 and output an electric signal
through the glass terminals (not shown). A pair of ribbon ground
wires 91, 92 welded to the base 113, are wired on both sides of the
wires 116, 117.
The metal container 112 is accommodated in cylindrical metal
fitting 119 having a collar 103 at an end thereof. The metal
fitting 119 and the metal container 112, whose external surface is
welded to the metal fittings 119, constitute the module main body
101. An optical fiber holder (ferrule) 122 for holding the optical
fiber core wire 121 therethrough is arranged on the side opposite
to the photo diode 111 with respect to the lens 114 and its brims
are welded to a side of the metal fittings 119. The optical fiber
holder 122 is covered with a protective rubber tube 123.
The thus-constructed optical receiver module 53 is accommodated in
the module receptacle 71 as shown in FIGS. 9A-9E, and is connected
to the printed circuit board 81 as shown in FIG. 7.
FIG. 11A is a longitudinal sectional view of the optical
transmitter module 54. FIGS. 11B and 11C are traverse sectional
(and elevational) views of same taken from the wire side and
optical fiber side, respectively.
The optical transmitter module 54 houses a sealed metal container
126, similar to that of the optical receiver module 53 and having a
laser diode and a monitor photo diode built therein and which is
connected to the optical fiber 56. The metal container 126 is
enclosed by a cylindrical container 126 having a collar 125 formed
thereon. The cylindrical container 126 is made of two semicircular
(i.e., in cross-section) synthetic-resin halves fused together or
bonded together with an adhesive along the vertical lines shown in
FIGS. 11B and 11C.
One (127) of three wires from the metal container 112 outputs a
circuit ground via the metal container 112. The other two (128)
respectively supply power to the laser diode and connect to the
monitor photo diode through the glass terminals (not shown).
The collar 125 has upper and lower flats 129 formed in parallel
with each other so that it is settled stably in a collar-receiving
recess 78 (see FIG. 7) of the module receptacle 72. The optical
transmitter module 54 is accommodated in the module receptacle 72
(see the description of FIGS. 9A-9E) and connected to the printed
circuit board 81 in the same way as the optical receiver module
53.
FIG. 12A is a plan view of a connection between the optical
receiver module 53 and printed circuit board 81. FIG. 12B is a side
view of same taken from the wire side. As described above, the
optical receiver module 53 is placed in the casing-body module
receptacle 71 and fastened with the metal clamp 86. Also, it is
accommodated stably in position with the collar 103 settled in the
collar-receiving recess 77.
The ground wire 116 for outputting circuit ground from the internal
circuits via the metal container 112 is soldered to the connection
pattern 131 of the printed circuit board 81. The power wire for
supplying power to the preamplifier IC and the power wire for
supplying a bias voltage to the photo diode are both soldered to a
common power connection pattern 132. The wire for outputting an
electric signal is connected to a signal connection pattern 133. A
pair of the ribbon ground wires 91, 92 from the metal-container
base 113 are connected to the respective ground connection patterns
93, 94 printed on both sides of the connection patterns 131, 132,
133 of the printed circuit board 81.
In order not to be influenced on the signal detecting ability, the
conventional optical receiver module, which did not take such
grounding measures as mentioned above, had to be spaced apart from
a source of electromagnetic interference by approximately 2 meters.
However, the inventors have confirmed by experiment that the
optical receiver module 53 of the present invention need only be
apart from the source by approximately 70 centimeters. They have
also confirmed that two ground wires 91, 92 provided on both sides
of the metal container 112 can achieve more effect than only one
can and that providing more ground wires at appropriate places is
more effective.
FIG. 13A is a plan view of a connection between the optical
transmitter module 54 and printed circuit board 81. FIG. 13B is a
side view of same taken from the wire side. As described above, the
optical transmitter module 54 is placed in the casing-body module
receptacle 72, fastened with the clamping metal 86. It is
accommodated stably in position with the collar 125 settled in the
collar-receiving recess 78.
The ground wire 127 for outputting circuit ground from the internal
circuits via the metal container 117 is soldered to the
printed-circuit-board connection pattern 136. The wire for
supplying power to the laser diode is soldered to the power
connection pattern 137. The wires for connecting to the monitor
photo diode are soldered to patterns 138, 139.
FIGS. 14A-14C are inside, front and side plan views, respectively
of a casing lid. It is assumed in FIG. 14A that the right, left,
upper, lower, reverse and obverse sides of the page are the front,
rear, right, left, top and bottom sides of the module,
respectively.
The casing cover 151 is molded as a one-piece construction, out of
such synthetic resin having excellent moldability and strength as
ABS resin. It is shaped like a container having the top plate 152
surrounded by a wall 153. The wall 153 has a step 154 formed on top
where the inner brim is lower than the outer and has right and left
recesses 155 in the middle for receiving the casing-body claws 65.
Claws 156 and 157 are provided on the front- and rear-sides wall
153, at positions where they engage the casing-body grooves 69 and
73, respectively.
An optical receiver module receptacle 161 and an optical
transmitter module receptacle 162 extend in parallel from the
front-side wall, with each of the bottoms being as deep as the
level of the step 154. These module receptacles 161, 162, which are
almost symmetric to those (71, 72) of the casing body 61, cover the
optical receiver and transmitter modules accommodated in the casing
body 61.
The so-constructed casing cover 151 is metallized on the whole
surface thereof through a process, for example, of electroless
plating, copper plating and nickel-plating for glossy
finishing.
FIG. 15A is a longitudinal sectional view of the assembled optical
transceiver unit, with both the rear- and front-side claws 156, 157
latched with the casing-body grooves 69 and 73, respectively. FIG.
15B is a traverse sectional view of same.
The printed circuit board 81, optical receiver module 53 and
optical transmitter module 54 are mounted in the casing body 61 and
the wires are soldered to the connection patterns as shown in FIG.
7. Then, the casing cover 151 is positioned on the casing body 61
with the claws 156, 157 extending downwardly (see FIGS. 14A-14C) so
that they align with the casing-body grooves 69, 73, respectively.
In this state, pressing down the casing cover 151 inserts the claws
156, 157 into the grooves 69, 73 with the claws 156, 157
elastically-deforming outwardly. When the bottom of the
casing-cover wall 153 touches the top of casing-body wall 62, the
tips of the claws 156, 157 elastically-restore to engage with the
recesses 74 of the grooves 69, 73 as shown in FIG. 15A.
FIG. 15 B shows the state in which the brim of the casing-cover
wall 153 touches the step 68 of casing-body wall 62 and the brim of
the casing-body wall 62 comes close to the step 154 of the
casing-cover wall 153. Thus, the casing-body metallized surface
electrically connects to the casing-cover metallized surface and
isolates the circuits included therein from the outside. Also, the
claws 156, 157 electrically connect to the recesses 74.
The optical transceiver unit of the second embodiment of the
present invention is explained below referring to FIGS.
16A-18B.
FIGS. 16A-16C are top, side and front views, respectively of a
casing body. FIG. 16D is a sectional view taken along the line A--A
of FIG. 16A. It is assumed in FIG. 16A that the right, left, upper,
lower, reverse and obverse sides of the page are the front, rear,
right, left, bottom and top sides of the module, respectively.
The casing body 171 is molded as a one-piece construction, out of a
synthetic resin having excellent moldability and strength such as
ABS resin. The casing body 171 is shaped like a container having a
base surrounded by a wall 62. For mounting a printed circuit board,
steps 63 of predetermined height above the base 64 are provided at
the four corners of the wall 62. Claws 65 for latching the printed
circuit board in position are provided on the right and left walls
62. Rectangular holes 66, 67 for letting (i.e., passing)
printed-circuit-board lead terminals therethrough are provided on
the right and left sides of the base 64.
The wall 62 has a step 68 formed on top edge thereof whereby the
inner brim is higher than the one. Grooves 69 for receiving
casing-lid claws are provided on the outer parts of the rear-side
wall 62. Module receptacles 71, 72 for holding an optical receiver
module and an optical transmitter module, respectively are arranged
in parallel on the front-side wall 62. Grooves 73 for receiving
casing-cover claws are provided on both sidewalls of the wall
62.
In this embodiment, recesses 74 are provided in the respective
grooves 69, 73 at places higher than the steps 69 of the wall 62.
Thus, in the casing body 61 of this embodiment, the distance
between the top of the wall 62 and the step 68 is larger than that
in the first embodiment. The module receptacles 71, 72, which are
different in size, are provided respectively with semicircular
recesses 75, 76 where the respective modules fit, collar-holding
recesses 77, 78 and clamp-inserting holes 79.
The so-constructed casing body 171 is metallized on the whole
surface through a process, for example, of electroless plating,
copper plating and nickel-plating for glossy finishing.
FIGS. 17A-17C are inside, front and side views, respectively of a
casing cover. It is assumed in FIG. 17A that the right, left,
upper, lower, reverse and obverse sides of the page are the front,
rear, right, left, top and bottom sides of the module,
respectively.
The casing cover 171 is molded as a one-piece construction, out of
such synthetic resin having excellent moldability and strength as
ABS resin. The casing body 171 is shaped like a container having a
top 152 surrounded by a wall 153. The wall 153 has a step 154
formed on top, where the inner brim is lower than the outer and has
right and left recesses 155 in the middle for receiving the claws
65 of the casing body 61. Claws 156, 157 are provided at positions
of the front- and rear-sides of the wall 153 where they engage with
the casing-body grooves 69 and 73, respectively. Here, claws 156,
157 are formed on the walls 153, at places lower than the step 154,
unlike those of the first embodiment which extend downward from the
brim.
An optical receiver module receptacle 161 and an optical
transmitter module receptacle 162 are provided in parallel on the
front-side wall, with each of the bottoms being as deep as the
level of the step 154. These module receptacles 161, 162, which are
almost symmetric to those (71, 72) for the casing body 61, cover
the optical receiver and transmitter modules accommodated in the
casing body 171. The so-constructed casing cover 171 is metallized
on the whole surface through a process, for example, of electroless
plating, copper plating and nickel-plating for glossy
finishing.
The printed circuit board 81 can be accommodated in the casing body
171 according to the same procedure as illustrated referring to
FIG. 7 and FIGS. 8A-8C with the reference number 61 replaced by
171. In the same way, the optical receiver module 53 and optical
transmitter module 54 can be accommodated in the casing body 171
according to the same procedure as illustrated referring to FIG. 7
and FIGS. 9A-9E with the reference number 61 replaced by 171.
FIG. 18A is a side view in cross section of the assembled optical
transceiver unit, with both the rear- and front-side claws 156 and
157 latched with the casing-body grooves 69 and 73, respectively.
FIG. 18B is a front view in cross section of the assembled optical
transceiver unit.
The printed circuit board 81, optical receiver module 53 and
optical transmitter module 54 are mounted in the casing body 171
and the wires are soldered to the connection patterns as shown in
FIGS. 17A-17C. Then, the casing cover 175 is positioned on the
casing body 61 with the claws 156, 157 directed downwardly (see
FIGS. 14A-14C) so that they align with the casing-body grooves 69,
73, respectively. In this state, pressing down the casing cover 175
inserts the claws 156, 157 into the grooves 69, 73 with the claws
156, 157 elastically-deforming outward. When the brim of the
casing-lid wall 153 touches that of casing-body wall 62, the tips
of the claws 156, 157 elastically-restore to engage with the
recesses 74 of the grooves 69, 73 as shown in FIG. 17A.
FIG. 18B shows the state in which the brim of the casing-lid wall
153 touches that of casing-body wall 62, which comes close to the
step 154 of the casing-lid wall 153. Thus, the casing-body
metallized surface electrically connects to the casing-lid
metallized surface and isolates the circuits included therein from
the outside. Also, the claws 156, 157 electrically connect to the
respective recesses 74.
The fact that the claws 156, 157 are formed on the casing-lid walls
153 and thus the walls 153 elastically-deform in the second
embodiment helps provide large latching force and prevent the the
casing cover 175 from being removed erroneously, unlike the first
embodiment in which the plate projections on which the claws are
formed elastically-deform.
An optical receiver unit of the third embodiment of the present
invention is explained below, referring to FIGS. 19A-21C.
FIGS. 19A and 19B are top and side external views, respectively of
the optical receiver unit of the third embodiment of the present
invention. FIG. 20A is a top view of the casing body of a main body
182. Side and front views correspond to FIGS. 6B and 6C or FIGS.
16B and 16C. It is assumed in FIG. 20A that the right, left, upper,
lower, reverse and obverse sides of the page to are front, rear,
right, left, bottom and top sides of the module, respectively.
An optical receiver module 53 is mounted on the
optical-transceiver-unit main body 182. Optical fiber 55 is
connected at one end to the module 53 and at the other end to an
optical connector 57. The casing body 183 is molded as a one-piece
construction, out of such synthetic resin having excellent
moldability and strength as ABS resin. The casing body 183 is
shaped like a container having a base 64 surrounded by a wall
62.
For mounting a printed circuit board, steps 63 of predetermined
height above the base 64 are provided at four corners of the wall
62. Claws 65 for latching the printed circuit board in position are
provided on the right and left sides of the walls 62. A rectangular
hole 66 for letting in (i.e., passing through)
printed-circuit-board lead terminals is provided on the right and
left sides of the base 64. The wall 62 has a step 68 formed on top,
where the inner brim is higher than the outer. Grooves 69 for
receiving casing-cover claws are provided right and left on the
outside of the rear-side wall 62.
A module receptacle 71 for holding the optical receiver module
extends from the front-side wall 62. Grooves 73 for receiving
casing-lid claws are provided on the wall 62, on both sides of the
module receptacle 71. The grooves 69, 73 each have a recess 74
formed between the bottom end and the casing-body base 64. The
module receptacle 71 is provided with semicircular recess 75 where
the external form of the module fits, collar-holding recess 77 and
clamp-inserting hole 79. The so-constructed casing body 183 is
metallized on the whole surface through a process, for example, of
electroless plating, copper plating and nickel-plating for glossy
finishing.
FIG. 20B shows the casing body 183 with the printed circuit board
811 and optical receiver module 53 mounted thereon.
The multi-layer (4- or 8-layer) printed circuit board 811 fits in
an area (board receptacle) formed by the casing-body wall 62, with
the reverse side placed on steps 63 at the four corners of the
casing body 61 and with the right and left sides engaged with the
claws 65. Since the printed circuit board 811 contacts the steps 63
at the four corners, the ground patterns printed on the four
reverse-side corners is connected to the metallized casing-body
surface via the upper surface of the steps 63, thus grounding the
metallized casing-body surface.
For easy understanding, electronic parts mounted on the printed
circuit board 811 are not shown in FIG. 20B. The printed circuit
board 811 has lead terminals 85 arranged in line on the right side
at a predetermined pitch and extending downwardly through the
casing-body rectangular holes 66. The lead terminals 85 connect to
a main printed-circuit board on which the optical receiver unit is
mounted.
The optical receiver module 53 is placed in a casing-body module
receptacle 71 and fastened there with a metal clamp 86. The optical
receiver module 53 houses a sealed metal container having a photo
diode circuit and a preamplifier IC built in. The optical receiver
module 53 is light-to-light connected to an optical fiber 55.
Four wires from the sealed metal container are soldered to
respective connection patterns 88 printed on a side of the printed
circuit board 811. One of the wires outputs circuit ground of the
aforesaid internal circuits via the metal container. The other one
outputs an electric signal through a glass terminal (not shown).
The other two, which are connected to a common connection terminal,
respectively supply power to the preamplifier IC, supply a bias
voltage to the photo diode through the glass terminals. Two
additional ground wires 91, 92 are provided on both sides of the
metal container, in parallel with the surface of the printed
circuit board 81 and soldered to ground patterns 93, 94. The
inventors have confirmed by experiment that providing more ground
wires is more effective in reducing the influence of
electromagnetic interference on the optical receiver unit. A
received signal processing LSI chip 96 is resin-sealed on the
reverse side of the printed circuit board 811 in the area enclosed
in a dotted line in FIG. 20B.
The printed circuit board 811 can be mounted in the casing body 183
according to the same procedure as illustrated referring to FIGS.
8A-8C. Also, the optical receiver module 53 can be accommodated in
the module receptacle according to the same procedure as
illustrated referring to FIGS. 9A-9E. FIGS. 10A-10C, FIGS. 12A
& 12B and FIGS. 15A to 18B may also be referred to as
necessary.
FIGS. 21A-21C are inside, front and side views, respectively of a
casing cover. It is assumed in FIG. 21A that the right, left,
upper, lower, reverse and obverse sides of the page are the front,
rear, right, left, top and bottom sides of the module,
respectively.
The casing cover 185 is molded as a one-piece construction, out of
such synthetic resin having excellent moldability and strength as
ABS resin. The casing cover 185 is shaped like a container having
the top plate 152 surrounded by a wall 153. The wall 153 has a step
154 formed on top where the inner brim is lower than the outer and
has right and left recesses 155 in the middle for receiving the
casing-body claws 65. Claws 156 and 157 are provided on the front
and rear sides of the wall 153, at the positions where they engage
the casing-body grooves 69 and 73, respectively.
An optical receiver module receptacle 161 extends forward from the
front-side wall, with each of the bottoms as deep as the level of
the step 154. The module receptacle 161, which is almost symmetric
to that (71) of the casing body 183, covers the optical receiver
module accommodated in the casing body 61. The so-constructed
casing cover 185 is metallized on the whole surface through a
process, for example, of electroless plating, copper plating and
nickel-plating for glossy finishing.
The optical receiver unit can be assembled as shown in FIGS. 19A
and 19B by mounting the printed circuit board and the optical
receiver module on the casing body 183 and then fixing the casing
cover 185 (as shown FIGS. 21A-21C) onto the casing body 183. That
is, optical receiver unit can be assembled according to the same
procedure as illustrated referring to FIGS. 15A and 15B with the
reference number 81 (printed circuit board), 61 (casing body) and
151 (casing lid) replaced by 811, 183 and 185, respectively.
The optical transceiver unit of the third embodiment of the present
invention is explained below.
FIGS. 19A-20B and the related description of the optical receiver
unit can apply to those of the optical transmitter unit by
replacing the optical receiver unit with the optical transmitter
unit and replacing the receiving signal processor LSI chip 96 with
the transmitting signal processor LSI chip 97. In this embodiment,
it is a design choice whether to form a metallized surface on the
casing body.
The optical transceiver unit of the fifth embodiment of the present
invention is explained below.
In place of the synthetic resin making the casing body and the
casing cover in the aforesaid first to fourth embodiment, synthetic
resin mixed with a material having excellent thermal conductivity
(e.g., approximately 5 to 10 percent aluminum powder or aluminum
short fiber by weight) can be used for making both or either of the
casing body and the casing cover. Thus, the heat generated by the
internal circuits can be dissipated efficiently from the unit.
Moreover, the inventors have confirmed by experiment that combining
other heat output means to the above configuration can be more
effective.
For easy understanding, the casing body and casing cover are
explained to be metallized over the whole surface. However, only
the portions which are invisible from outside when they are
combined each other, i.e., only the interior surfaces need be
metallized, since the portions where they contact each other are
connected electrically to each other, accordingly isolating the
internal circuits from the outside.
The optical receiver and transmitter modules may be arranged not
necessarily in parallel, but in a direction opposite or
perpendicular to each other.
Further, the claws for latching the casing cover with the casing
body may be provided on the casing body or both the casing cover
and the casing body.
In summary, since the optical receiver unit, for example, of the
present invention is so-constructed, it can easily be assembled as
follows. Pressing down the printed circuit board into the
casing-body board receptacle automatically latches the printed
circuit board in position by means of the claws. Inserting the
metal fittings into the casing-body holes with the optical receiver
module accommodated in the receiver module receptacle fastens and
fixes the optical receiver module to the casing body. Finally,
connecting the wires completes the process to install the optical
receiver module to the casing body.
Next, pressing down the casing cover onto the casing body
automatically latches the casing cover to the casing body by means
of the claws and thus, completing the optical receiver unit which
can electrically isolate the internal circuits from the
outside.
By the same process as for the optical receiver unit, the optical
transmitter unit and the optical transceiver unit can easily be
completed.
Since, in the optical receiver module, two additional ground wires
from the metal container are connected to the printed-circuit-board
ground patterns via both (i.e., respective, opposite) sides of the
metal container, the opto-electric converter circuit is protected
from external electromagnetic interference. By making the casing
body and casing cover of a material having excellent thermal
conductivity mixed with synthetic resin, the heat generated by the
internal circuit can be dissipated efficiently from the unit.
As described above, the present invention can achieve an optical
transceiver unit which is simple in configuration, small-sized,
light-weight and easy in assembling and which are reliable and
proof against electromagnetic interference.
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